Gyroscopic navigational instrument



April 21, 1953 Filed May 12, 1951 T. o. SUMMERS, JR 2,635,469

GYROSCOPIC NAVIGATIONAL iNSTRUMENT 8 Sheet s-Sheet 1 THO/#75 0. SUMMERS, JR.

INVENTOR.

BY fl w nrmeA/EV A ril 21, 1953 T. o. SUMMERS, JR 2,635,469

GYROSCOPIC NAVIGATIONAL INSTRUMENT Filed May 12, 1951 8 Sheets-Sheet 2 usei :54 :55 v P mow/7s 0. SUMMEQS, ue,

[ 57 INVENTOR. B 14| BY 4m 7" A ril 21, 1953 T. o. SUMMERS, JR

GYROSCOPIC NAVIGATIONAL INSTRUMENT 8 Sheets-Sheet 5 Filed May 12, 1951 INVENTOR.

BY KQ Q a E M W s a w M w FTTOENEV April 21, 1953 T. o. SUMMERS, JR 2,635,469

GYROSCOPIC NAVIGATIONAL INSTRUMENT Filed May 12, 1951 s sheets-sheet 4 April 21, 1953 "r; o. SUMMERS, JR 2,635,469

GYROSCOPIC NAVIGATIONAL INSTRUMENT Filed May 12, 1951 s Sheets-Sheet 5 7 IIIIIII/ MUM/75' 0. Sal/MEGS, d9.

- IN VEN TOR.

April 21, 1953 T. o. SUMMERS, JR 2,635,469

GYROSCOPIC NAVIGATIONAL INSTRUMENT Filed May 12, 1951 8 Sheets-Sheet 6 if Y: I 'i 67 69 e5 firm/n5 a. sum/made k 68 INVENTOR.

BYKX QMMDAM,

HTTOQA/EV April 1953 'r. o. SUMMERS, JR 2,635,469

GYROSCOPIC NAVIGATIONAL INSTRUMENT 13 I 4 INVENTOR. g .I BY W Y HTTOENEI April 1953 T. o. SUMMERS, JR 2,635,469

GYROSCOPIC NAVIGATIONAL INSTRUMENT Filed May 12, 1951 Sheets-Sheet 8 I68 f I 169% no; no I27 IN V EN TOR.

HTTOEA/Ei Patented Apr. 21, 1953 UNITED STATES? PATENT OFFICE GYROSUOPIGNAVIIGATIONAD INSTRUMENT Thomas-0: Summers, J r., ShermamOaks, Galifii Application May-'12, 1951,, Serial No. 225.997,

28 Glaims;

. 1 This inventionrel'ates the; control and/or navigation of aircraft; and more specifically, to a control gyroscope. One

example of'a control system of theclassto which this invention relates is theconventional aircraft horizon" indicating gyroscope; Such an indica= tor isused' to provide'the pilot of anaircraftwith horizontal and" vertical reference planes which remairr substantially fixed" with respect tdthe earths surface; in thenavigation of aircraftund'er conditionsof' poor'visibility or'in' the absence of a real horizon for the reason' that departures of the aircraft: from 'a' desired pitch attitude can be" visually detected and manually corrected: Also,'departures of" the aircraft" in roll from a wing level attitude are discerniblewith' the "result that even in the absence. of the real'horizontal, it is possible? for the'pilot'of'an aircraft to fly a'wing level course; However; in ordertofiy'a straightcourse, itis' sometimes necessary'to fly "with the wings other than level to account for inherentout-of-trim conditions. A perfectly trimmed aircraft'mayfiy straight'when itsJwings are level, but due to in herent wingimperfections thaticannotbe avoided: inaircraftfabrication; an aircraftmay be out oi trim inrollwiththeresultthat, if its wingsare' maintained level, itwill turnone way or the other: Whenever the vectorsum ofall'the aerodynamic lift forces is vertical, the aircraft 'will'fly straight; but under other conditions; a turn will result whichwill be a function" of the degree 01 tilt of thelift" vector. Therefore, conventionarh'orizon indicators; while providing control means for maintaining a wing level attitude, do notnecessarily provide reference means formain'taining' straightfiight;

It is therefore an object'ofthe presentin'vention to provide a gyroscopic instrumenttoesr tablish the vertical plane in spaceabout thepitch' axis of the craft and the resultantlift'or straight flight" plane rather than the vertical plane. in space in so far as the roll axis of'thegyroscope is concerned To this endtlie gyroscope ofjthe invention isconstructedso as to be gravity erected. in'pitch andcase erectedin' roll. By caseerect ingthe gyroscopein roll; the spin axis is erected to the average position in spaceassumed by the. aircraft'about its. rollfaxi's. Since the pilot'of an aircraft has other navigationalaids, such as a di w rectional gyro and/ or a rate of turn indicator, he is able to fly in a generally straightdirection and; therefore; .the average position in space of the; aircraft about its :roll axis is substantially that position'atwhich the aircraft will fly straight; A'

to a control system for Such gyro verticals are useful" case-erected gyro roll reference seeks this aver-- age position and, therefore, providesthepilot with an improved rollreference to which he may quickly return in theevent of an undesired-disturbance. Such a reference-makes it possible for the-pilot to-holdis aircraft-in roll at=that positionat which the aircraft will fly in a straight-path. A conventional graV-ity' erected' gyro horizon on the-other hand will make possible the return ofthe aircraft to a wing-levelatti'tude, but not necessa-rily-to that attitude rollat which the aircraft will fly straight;

While, perhaps-itis not newto gravity erect and caseerect a-reference gyroscope, it has-not heretofore been considered feasible to utilize case erection for the purpose of--contro1lingthe aircraft in roll, foritwas erroneously assumed that to case erect, or in other words, to permitthe aircraft to establish its own-roll reference was synonymousto omitting gravitational influence,

or roll'control; about a'posi-tion fixed with respect to-the earths surface. Actually, to creat the gyroscope to a position in space established by -the aircraft; itself doesnet' mean thatareference -planesubstantially fixed with respect to the earths surface is not established. Ari-airplaneds an extremely gravity sensitive mass supported-orra-ir, and the slightest departure roll fromthat' one position with respect tothe earthssurface at which itfliesstraight is' evidenced bya-turn:

Thegyroscope ofthisinvention can -be-ineluded as a component of a navigationalinstrument to provide control signals for the craft, and therefore-it is anobject of" the invention to provide a control system for-utilizing these reference' signals to control both pitch and rollofthe craft. If desired: a-visna-l indicator for the-pilot'can- -be providedj'which is responsive to gyro position-and which can be utilizedby r a: human pilot to guide the craft;

Another advantage" ofthegyroscope of the present invention becomes evident when it is employedin conjunction with rotary launchers; severaltypes oftarget airoraftarenow launched by a: rotary type "oflauncher; which comprises a circularftrackjto accommodate a target whichis tied to'a'pyl'orrby aflexib'lelink". Such a launchermakes it possible f or an :aircraft' or" missile to "at-- tain;fiying speed'underi its own power; although the craft; is confinedlto' a small area: A target aircraftfso launched'may m ake'many revolutions with its wingsperfectly horizontal; Under such conditions a conventional type offgyro vertical wouldpre'cess andwith the resultthat when the craft was released from the launcher, it would go into a turn, which might result in the loss of the craft. With the gyroscope of the present invention, the aircraft may circle the launching path indefinitely, and upon launching, there will be no error, since the wings of the craft are confined to the horizontal during launching. It is therefore a further object of the present invention to provide a gyroscope which will be unaffected by acceleration forces encountered by the mounting craft when launched from a rotary type launcher.

These objects and other objects, not particularly enumerated above, will become fully apparent from the following description when considered in connection with the accompanying drawings in which:

Fig. 1 is a top plan view of the casing for the navigational instrument of this invention.

Fig. 2 is a front view in elevation of the instrument casing looking in the direction of arrows 2-2 of Fig. 1.

Fig. 3 is a horizontal section of the navigationa1 instrument along line 3--3 of Fig. 2.

Fig. 4 is a horizontal section of the valve control mechanism as shown in Fig. 3 with the valve in open position.

Fig. 5 is an enlarged vertical section taken along line 55 of Fig. 3 with the inner gimbal and gyro rotor shown in side elevation. V

. Fig. 6 is a transverse section taken along line 8-6 of Fig. 5 showing the inner gimbal in section and the gyro rotor in elevation.

Fig. 7 is a view similar to Fig. 6 showing the outer gimbal and pendulous bail in elevation.

Fig. 8 is a transverse section taken along line 8-8 of Fig. 5 showing engagement of the contact plates.

Fig. 9 is an auxiliary view taken along line 9-9 of Fig. 8 showing the pick-off for pitch control.

Fig. 10 is a sectional view along line ||0 of Fig. showing pick-01f assembly for pitch control.

Fig. 11 is a vertical section taken on line of Fig. 6 showing the pick-off assembly for roll control.

Fig. 12 is a plan view of the gyro erecting assembly taken along line |2--|2 of Fig. 6.

Fig. 13 is a schematic wiring diagram for utilizing the control signals of the navigational instrument to control flight of the craft.

Fig. 14 is a view similar to Fig. 7 showing a visual indicator connected to the inner gimbal of the gyroscope.

Fig. 15 is a view in front elevation taken in direction of arrows |5|5 of Fig. 14 showing the visual indicator.

The gyroscopic navigational instrument of this invention is comprised of a divided casing I, which has an extension 2 for housing the pressure sensitive element and an extension 3 for housing the valve control mechanism. The projections 4 on divided casing I are threaded to receive screws 5 which pass through opening in mounting brackets 6. The mounting brackets are rigidly attached to the aircraft and therefore serve to mount the gyroscopic navigational instrument within the aircraft. The direction flight of the aircraft is indicated by the arrows shown in a number of the figures. A mounting bracket 1 is integral with casing and projects into the interior of the casing to provide a support for the gyroscope and for the electrical circuits. A member 8 is secured to the end of bracket 1 by screws 9 and, together with bracket 1, provides an opening for receiving the screw threaded circular bearing housing l0 (see Fig. 8). Within housing H! is positioned a bearing race for ball bearings The outer gimbal |2 of the gyroscope, utilized in the navigational instrument of this invention, has a threaded opening for receiving a shaft supporting member l3, which terminates at one end in a shaft M. The shaft l4 projects into housing In and carries a bearing race which cooperates with ball bearings so as to provide one of the pivotal supports for outer gimbal l2. A second shaft supporting member I5 is threaded to the outer gimbal |2 at a position 180 degrees from member |3 and terminates in a shaft IS. A circular bearing housing having external threads, is screwed into an opening in casing and supports a bearing race for ball bearings I8. Shaft |6 extends within housing I! and cooperates with bearings |8 to provide the second pivotal support for outer gimbal l2.

The outer gimbal I2 has two openings, positioned at degrees from shafts l4 and I6, which receive externally threaded, circular bearing housings l9 and 20 for housing ball bearings 2| and 22, respectively. The inner gimbal 23 of the gyroscope is provided with shafts 24 and 25 which extend through bearing housings I8 and 20 respectively and cooperated with the ball bearings within the housings to pivotally support the inner gimbal 23. The motor 26 for spinning the gyro rotor 26a is supported within the inner gimbal and the rotor dome 21 is attached to the lower end of the rotor so as to spin with the rotor. In order to balance the inner gimbal, a. balancing weight 28 of naval brass is secured to the upper part f the gimbal and is provided with balancing screws 28 for adjusting the effective position of the balancing weight. The function of the rotor dome will be discussed in connection wtih the description of the gyroscope erecting means.

The electrical supply for the gyro rotor motor and for the roll and pitch pick-off assemblies is provided through cannon plug 3|] which has ten leads into the casing Six of these leads connect with a set of six electrical contacts plates 3|, 32, 33, 34, 35 and 38 which are mounted on bracket 1 by means f insulated screws 31 secured thereto. These contacts plates are separated from one another by insulated sections mounted upon screws 31. An arm 38, rigid with outer gimbal l2, carries a second set of six contact plates 39, 40, 4|, 42, 43, and 44 which bear respectively against plates 3|, 32, 33, 34, 35 and 38 to provide means for supplying electrical power to the components of the gyroscope which do not move with the casing and the aircraft. Insulated screws 45 secure the second set of plates to arm 38 and insulated sections are carried by screws 45 to separate each plate.

In order to supply electrical power to the gyro motor, the positive contact plate 39 is connected by lead 45 to conducting plate 41 (see Fig. 3). This plate is mounted on the outer gimbal l2 by means of insulated screws 48 and the plate continually bears against silver pin 49 which passes through the inner gimbal shaft 24 and connects with lead 50. Insulating cylinder 48a separates pin 49 from shaft 24. A slot 5| is provided in the inner gimbal 23 to allow the lead 58 to connect with the gyro motor 26. The negative contact plate 40 is connected by lead 52 to the outer gimbal (see Fig. 7) so as to ground the outer gimbal at all times. Also, attached to the outer gimbal by rivets; 53Eis.z:the: silver: wire: fork 54; WhiQhTIQOI'I-F' tinuallybears: against :contact :cylinder 55 mount-.- ed in the endof shaft 24. andinsulated'fr'omisilver pints: by insulating-cylinder:49d. Since the re+ turn lead. (not. shown) for. the .gyro .motor. is; attached to. the. inner gimbal 23; the motorr is grounded-:t theouter. gimbal through shaft124,i contact. cylinder. 55. and silver fork 54... This cire cuit; provided for the gyromotor, allows themotor to operate regardless of the relative positions assumedv by the motor andthe instrumenttcasing I.

Erectionof yro An important feature of the. present inven-. tion is, the. useofia. yroscope 5. av y. erected in pitch and case. erected in roll; In' order, to accomplish this resultr av pendulous bail 56 is provided. which. is free. to moveabout. the transverseaxis of the aircraft butnot about the longitudinal axis thereof. The bail 56 curves. around the gyro dome Z'Iand has a circular opening ateach end for receiving the outer races of ballbearings 57 and 58. A shaft 59 extends inwardly from member [3 and is received by ball bearings 5's while shaft 61) extends inwardly from member I5 and is received by ball bearings 58. Consequently, the shafts 59 and 60 provide means for pivotally supporting bail 56. so that it is free. to rotate about the transverse axis of the aircraft.

'ihe. erecting means for the gyroscope, is positioned in a cut out portion at the lower center of bail and is comprised of a mounting plate 6i which is secured to the bail by means of screws 52 and B3. The plate 8| extends to one side of the bail and contains three narrow slits 64 which form two sections 65 in the plate. These sections. project past the edge. of the .plate and are bent downwardlyto act as a stop for the bail. A buifer ring 56 is placed around the ends of sections 55 to prevent a sudden contact between the ends of the sections and the two stops 66a. The triangular erector platetl is attached to mounting plate Bl by rivets 68 and is sprung outwardly from plate 6| by screw 69. The erector In is formed as asmall upward projection on erector plate 5'! and bearsagainst the gyro dome 21 with a force determined by the. adjustment of screw 69. When both the gyro spin axis and bailassume true vertical, the erector, it will be along" the spin axis of thegyroscope... Astop, H ismounted by screw 62 on plate a i andprevents erector plate 51 from being sprung an excessive amount.

The erector 'H] of this invention functions in accordance with the same principal'as doesthe caging pin shown and described in U. S. Patent No. 2,412,481 to T. O. Summers, Jr. dated Dee cember 10, 1946; Since the erector Iii continually bears against spinning dome 27, any movement of the erector away from the spin axis will result in precession of the gyroscope until the spin axis is. again brought into line with the erector. This result because of the fact that when the erector is not in line with the spin axis, it exerts a friction force upon the dome and the gyroscope which is at right angles to the line, between the spin axis and the erector. This, friction, force will cause the gyro to precess in a direction at right angles to the friction force and in a direction toward the erector. Thus, when movements of the erector 'iutake place, the gyroscope will con-.- tinually precess and the spin axis will follow the, erector 10.

Since the pendulous bail 56' is pivoted-about thetransverse axis of the aircraft; the positionof 6. the bail; about: thepitchaxisi ofrtlie aircraft::.is determined by" gravitational forca and; because the erector iscarriedrby thebaih. the gyroscope will beerectedxtorgravity. vertical about the-pitch axis-atall times... However;.the baili5fi-fistnot free to move.about: the longitudinalaxisxof' the aircraft andsincethe shafts .59fandl8ll are rigidwith the casing, the bail'will move with the casing about .the longitudinal: axis.. Theerector. 10: will cause the gyro spin axis to follow: these move, ments of the casing and'therefore the gyroscope will be case erected. about -the-roll'axis; Thus, the reference established abouttherollaxis. by thegyroscopic willbe-that required for straight flight of the aircraft regardless :of the positionof the vectorsum of the lift forces acting uponthe aircraft. The establishment of'this reference is possible becausetheaircraft .w-ill'ily straight-most of the time and the position-of theerector will be determined by thepositlon of the. casing during straight fiightt The operation of erector Ill willbe further discussed; in connectionwith the operational description of'the navigational instrument of this invention.

Roll pick-017 assembly Inorder to control turning movements'ofthe aircraft, a roll pick-01f assembly is provided which includes a potentiometer winding 12 mountedingroove, l3jof insulatingring T4(see Eig. 11).. This ring is securedto outer gimbal 12 by means of screws 15: Alsomounted on ring 14 by screws iGjis a conducting plate l1, the'end' of which bears against, a projection on silver disk 18. The disk 18 is carried onthe otherface of insulating member l9, whichrcontains a circular opening for receiving the end of inner gim-y bal shaft 25. A set screw is. positionedin member 19 in .ordertofastenmember l9to shaft 25 sothat member 'lSrwill rotate with the inner gimbal of the gyroscope. A second silver disk, Bl is carried on the inner faceiofmember l9 and, bothdisks l8 and 81' are secured to member 79. by conducting rivets 82; A wiper arm '83, is soldered to disk 8| and projects across potentiometer winding 12. This arm is held in place by positioning. arm 84 which is likewise soldered to disk 8 l and has a loop at its end for receiving the. wiper arm. A- biasing screw 85 passesthrough member "59 and bears against disk 8| to provide for adjusting thepressure of wiper arm 83 against potentiometer winding 12.

A positive lead 86 connects with contact plate 4| and supplies. electricalenergy to wiper arm 83 throughplate Tl, disk 18, rivets '82 and disk 8|. One; end of potentiometer winding 12 connects with lead .81 while the otherend connects with lead 88. These leads 8-! and 88 pass through ring 1d and are connected respectively with contact plates 42 and 33. The winding 12 therefore acts as. a current divider and as long as the wiper armis positioned. in the center of the winding. equal currents will. flow through the two sides of the winding. However, when. the. wiper. arm moves away from the, center ofthewinding asa result of movement of the casing withrespect to the inner gimbal 23; unequal currents willfiow in-the two sides of thewinding-H. The wiring. circuit for the roll pick-off assembly is. shown in Fig: 13. andjwill be more fully explained'in connection with the operational description of this invention:

Pitch pick-01? assembly,

' Inorder to-control pitching movementsofth'e aircraft, a pitch pick-oft assembly is provided which corrects for changes in pitch of the aircraft as well as changes in altitude. This pickoff assembly is similar in construction and function to the one described in co-pending application Serial No. 170,719 filed June 28, 1950, by T. O. Summers, Jr., and includes an insulating member 89 which is attached to arm 38 by screws 45. Secured to member '99 is a bent aluminum plate 90 which projects to one side of member 89 and mounts a conducting plate 9I by means of rivets 92. A continuous wire 93 is bent to form a triangle plus a supporting arm and one leg of the triangle forms an angular wiper arm 94. Two legs of the triangle and the supporting arm are soldered to plate 9| and a screw 95, mounted in plate 90, bears against conducting plate 9I to provide means for adjusting the pressure exerted by wiper arm 94. A positive lead 99, connecting with contact plate 44, passes through plate 93 and connects with conducting plate 9| in order to supply electrical power to wiper arm 94.

The wiper arm 94 coacts with potentiometer winding 91, which moves with casing I, and therefore, movements of the casing with respect to the outer gimbal I2 will cause the wiper arm to change position on the winding 91. The winding is carried in groove 98 on the outside of insulated cup member 99, which is separated from disk I by spacingblock IOI. Screws I02 pass through block IN and fasten member 99 to disk I00. Three pins I03, I04 and I are positioned in member 99 at 120 degree intervals and have grooved ends to which attach one end of wires I06, I01 and I08 respectively. The other end of these wires attach to plates I09, H0 and III which are likewise placed 120 degrees apart and are riveted to a ring I I2 positioned between casing I and casing extension 2. The wires I06, I01 and I08 therefore serve to support and center the member 99 within the gyro casing and since wire I08 contains a coil spring section, it is possible for member 99 to move with disk I00 longitudinally of the casing extension. Lead I I3 connects one end of winding 91 with pin I03 and therefore completes a return circuit to lead II4 which passes directly to cannon plug 30. Another lead II5 connects the other end of winding 91 with pin I04 and completes the return circuit to lead I I6 which likewise passes directly to cannon plug 30. It is therefore seen that the current supplied by wiper arm 94 is divided by the winding 91 in a manner which depends upon the position of arm 94 on the winding.

Since the wiper arm is positioned angularly with respect to the winding '91, longitudinal movements of member 99, carrying the winding, will cause the point of contact of the wiper arm to change positions on the winding and thereby change the currents flowing in leads I I4 and I I6. Also, movements of the gyro casing relative to the outer gimbal resulting from changes in pitch of the aircraft will also cause relative movement between arm 94 and winding 91 and cause changes in the current flowing in leads H4 and H6. By using the angular wiper arm 94, it is possible to control both the pitch and altitude of the aircraft in a manner which will presently be described.

, A metallic bellows H1 is positioned in casing extension 2 and has one end attached to and closed by disk I00 while the other end is attached to and closed by member II8 which is secured to casing extension 2 by means of bolts H9. The member II8 has a circular extension I which passes through casing extension 2 and into an opening I2I in block I22 and also carries a pipe section I23 which extends across the inside of the bellows. A coaxial opening I24 passes through pipe section I23 and extension I20 and connects opening I2I with the inside of the bellows II1. A passage I25 in block I22 communicates with tube I25 which continually supplies atmospheric pressure to the inside of bellows.

To casing extension 3 is attached a member I21 having an opening I28 in communication with tube I29 which is continually connected to. atmosphere. The opening I28 also provides a continuous passage between tube I29 and tube I29 leading to bellows II1. An electromagnet I 30 is positioned within casing extension 3 and has leads I3I and I32 passing directly to cannon plug 30 through partition I33. The core I34 for the electromagnet I30 has an opening for receiving valve tube I35 which is fastened to and passes through armature I36 so as to be continually connected with the atmospheric pressure in opening I28. One end of tube I35 has a series of slots I31 and continually bears against valve member I38, which is contained in enlarged opening I39 in core I34. The valve member I38 is mounted on plate I40 which slides in opening I39 against the pressure of spring I4I, retained by means of snap ring I42 in opening I39. The plate I40 has sections cut away from its edges to provide a passage around the plate.

' The armature I36 is free to move in opening I28 and when the magnet I30 is inactive, spring I 4| acting against plate I40, forces slots I31 of tube I35 into core I34 and causes valve member I33 to close the passage in tube I35 (see Fig. 6). However, when the magnet I30 is energized, the armature I36 moves slots I31 of tube I35 into opening I39 and provides a passage from opening I28 through slots I31 and around plate I 40 and into the interior of the gyroscope casing (see Fig. 4). All sections of the gyro casing and casing extensions are provided with sealing rings I43 so that the casing is substantially air tight when pressure is trapped within the casing by valve member I38.

When control of the altitude of the aircraft is not desired, the magnet I30 is energized so that the inside of the gyro casing is open to atmosphere pressure and therefore, the pressure inside the casing changes with altitude. If altitude control is required, the magnet is deenergized and causes valve member I30 to trap within the gyro casing a pressure corresponding to that at the desired altitude. Since the inside of bellows [I1 is continually connected to atmosphere, any change in atmospheric pressure from that at the desired altitude will cause bellows H1 to bodily move winding 01 in a direction along its axis. This movement will cause the point of contact between angular wiper arm 94 and winding 91 to change so that unequal currents will flow through the two sides of the windings and thus the elevators of the aircraft will be moved in a direction to correct for the change in altitude. The pitch control of the aircraft is effective whether or not the altitude control is being utilized. When the aircraft changes pitch, the winding 91 will rotate with the gyro casing relative to wiper arm 94 but the winding can at the same time be moved along its axis to correct for altitude change. It is therefore obvious that by the coaction of the wiper arms 83 and 94 with windings 12 and 91 respectively, it is possible to control the roll, pitch and altitude of the air craft equipped with; the navigational. instrument of this invention.

Operation The control circuit and the servos which form a part of this invention are shown diagrammatically in Fig. 13. The casing I' houses the gyroscope and associated pick-offs while. the pilot controls are'located on instrument panel M4. A power source Hi has line I48 leading to the main switch I 41' located on the instrument panel. When this switch is closed by the pilot, power is supplied to the main line I58 which has a branch I49 leading to the-pitch servo I55 and a branch I 5i leading to the roll servo I52. These branches provide power for motors (not shown) which are contained in each of theservos-for develop-- ing power to move the aircraft surfaces. Theline I 48 is connected to the gyroscope motor 26 of this invention by means of lead 50 and the motor is grounded by lead 52.

The wiper arms 85 and 94 are also connected to line I48 in order to supply power-to windings I2 and 91 respectively. Oneend of winding I2 is directly connected to the roll servo I52- by lead I53 which contain a fixed resistance-I54 while theother end of the winding is connected'to the roll servo by lead I55 containing aresistance I55 which can be varied by manually movable wiper arm I51. In a similar manner, one end of winding 91 is connected with the pitch servo I5Ilthrough lead I56 containing fixed resistance" I59 while the other end is connected to the servo-by lead I60 containing a resistance IIiI" which can be varied by manually movable wiper arm I 62. It is pointed out that resistances I5I and I56 are twice the size-of-resistances I59 and I5 3 respectively'so that-the resistance in leads I5'3and I55 and inleads I58 and I60 can bebalancedby'centering'the'wiper arms I51 and I62. Theline I83 connects main line M8- with the electromagnet for the altitudecontrol valve is desired. The leads I65 and I65 both connect with ground I67 in order to'ground'all thepower lines which connect with pitch servo I5t'and'roll servo I52.

Both servos can be ofthe opposed magnetic clutch type wherein each servo has two clutches which coact with shafts rotating in opposite directions. The resultant output of the two clutches working against each other will then be proportional to the difference in current. flowing through the two clutches and this output will operate the control surfaces of the aircraft against the aerodynamic forces which tend" to streamline them. It is therefore possible to adjust the output of either servo so that it will maintain its control surface in any position desired for flight control.

If it is desired to place, the aircraft, equipped with this invention, on astraight and level course, the pilot would first adjust wiper. arm I51 until the aircraft maintains a straight course asindicatedv by. other flight instruments in the cockpit. Due to the unbalance of the lift forces of. most aircraft, the. wings, ofthe aircraft must he tilted. from the horizontal slightly if straight flight is to result. and therefore the ailerons controlled by servo I52 must be maintained in an appropriate positionin order to keep the wings suitably. tilted. Since thegyroscope of this invention. is. case' erected in, roll,. the wiper arm I 51 must be adjusted so that the position assumed by thegyroscope: and the wiper arm 83- for straight flight will cause unequal currents to flow in lines I53 and I55 which are'sufiiciently unequal to cause the servo to develop an output equal to the aerodynamic forces on the aileron when positioned for straight flight. Oncethe arm. I 5'! hasbeen-so adjusted, any deviations of the aircraft from straight flight will cause the.

winding I2 to move relative to wiper arm.8.3 and either increased or. decreased power will be pro..- vided by the roll servo to move the aileron in a direction to bring. the aircraft back to straight.

flight. Therefore, once. the. aircraft has been set on, a straight. course, the gyrowill be case. erected by the.erectingprecessor. III to. aposition.

which will provide the correct roll reference. for continued. straight. flight. of; the aircraft.

Inorder to leveloffthe aircraftequipped with. this invention, itmay be necessary for the pilot. to adjust wiper arm IE2 until the aircraft flies. a levelcourse as indicatedby the other flight in: strumenta. While. thisv adjustment is. made,.the.

switch. I 5.4 should be closedso that. the altitude...

controleffected by bellows. IIFI. wilLbeinactiva. Thus, it may be necessary for. arm. I62 to be.

placed in sucha positionbnwinding I 5i. that.

unequalcurrentswill flow in lines I58.-and. I60. to the. opposed magnetic-clutches of the pitch.

servo I56. The diiferencein.thecurrents willbe.

just sufiicient for the servo, tov develop apowen output equal to any aerodynamieforceon the. elevators which maybe requiredto maintain. the. aircraft in level flight. gravity erected in pitch by bail 55,.any. deviation of the. aircraft from. level flight willcause wind.

ing 9?. to move relative to the wiper arm 94 and readjustthe unbalance ofthe currents ..in.leads.

I58=and I50 sothatthe. servo. will-move theelevators ina directiomtobring. the-aircraftback. to'levelflight- It is therefore possible. to main tain-the aircraft on astraight. andlevel. course.

once the ailerons. andelevatorshavebeen posia tioned. to. maintain such a course.

In order to correct. for. changes in altitude;

which may result, as for example, when the air.- craft is caught in a-down draft, the switch I64.

can be released bythe pilot, thus trapping apressure within the airtight gyro casing corresponding to the atmospheric pressure at the-desiredaltitude of flight. Any change in altitude of the aircraft will result in a change in-the.

atmospheric pressure communicated to the inside. of bellows I-II- and a pressure differential will. result betweenthe inside of the-casing and the. inside of thebellows. This pressure differential: willcause winding 97 to move relative to an? gularly positionedwiper arm- 94' and cause suflicientcurrentunbalance between lines I 53 and. I 55;.

for the pitchservo to return the aircraft to the desiredaltitudeand then leveloif the aircraft.

If. itis desiredto-turn-the aircraft to the left.

or-the right, the pilot canmove the arm I51. either" to the left or the right of itsstraight flight position and. thereby unbalance the cur..- rents in lines I53 and I55:a suflicient amount to move the ailerons in thedirection and, in

the amountrequired toexecute-the desired rate. of turn. After" the turn is completed, thepilot.

can simp1y/returnarm' I5-I to its. position before the turn-in order tcresume straight flight. Also, the pitch of the aircraft' can be controlled bythe pilot by manually moving arm I62. up, or

down with respect to; its-leyel flight position to either increase orlower the altitude-0ftheair craft. When itiis required-to. level off the aira Since the. gyroscope. is.

craft after a desired change in altitude, the pilot need merely return arm I62 to its original position for level flight.

Visual indicator A modification of the invention is shown in Figs. 14 and 15 wherein a visual indicator is provided as a navigational aid for the pilot. One section of divided casing I is replaced by a transparent section Ia and supporting brackets I68 are secured to the casing by screws I69. The indicator I10 has a cylindrical projection I'll for receiving the end of shaft 25, which serves as one support for inner gimbal 23. The face of the indicator carries a series of transverse lines I12 and a vertical line I13. The transparent section Ia has a transverse indicating member H4, which has an enlarged opening H at its center through which the lines I12 on indicator I can be observed. The member I14 cooperates with the lines I12 to designate the amount of dive or climb of the aircraft. Also, a series of lines I16 are placed in an arc on the surface of transparent section la so as to cooperate with line I13 on the face of the indicator and designate the amount of turn of the aircraft either to the right or the left. Thus, when the aircraft goes into a turn or a change in pitch, the casing of the instrument will move with the aircraft relative to the gyroscope which has been erected for straight and level flight and any deviation from the straight and level flight condition can be visually observed by the pilot.

From the above description, it is apparent that the instrument of this invention can be relied upon to maintain the aircraft on a perfectly straight and level course regardless of the outof-trim forces inherent in the aircraft. For the purposes of the present disclosure, the terms craft and "aircraft" are interpreted as including all types of air, land and water craft, and all types of missiles and vehicles, in addition to the ordinary connotations associated with the words. Various modifications are contemplated and may obviously be resorted to by those skilled in the art, without departing from the spirit and scope of the invention, as hereinafter defined by the appended claims.

What is claimed is:

1. In a gyroscopic navigational instrument for an aircraft, a casing supported by said aircraft, a gyro rotor universally supported within said casing, means for case erecting said gyro rotor about the roll axis of said aircraft during straight flight to obtain a straight flight reference position for said rotor, means controlled by said gyro when in said reference position to correct for deviations of the aircraft from straight flight.

2. In a gyroscopic navigational instrument for an aircraft, a casing supported by said aircraft, a gyro rotor universally supported within said casing, means movable with said casing about the roll axis of said aircraft for erecting said rotor to a fixed position with respect to said casing, means for tilting said aircraft and the gyro rotor about said roll axis to a straight flight position and means under control of said gyro rotor when in said straight flight position for preventing the aircraft from turning.

3. In a gyroscopic navigational instrument for an aircraft, a casing rigid with said aircraft, a gyro rotor universally supported within said casing, means movable with said aircraft about its roll axis for erecting said rotor to a predetermined position with respect to said aircraft, said rotor being erected by said means to a straight flight reference position during straight flight of the aircraft, and means responsive to said gyro position to maintain said aircraft in straight flight.

4. In a gyroscopic navigational instrument for an aircraft, a casing rigidly secured to said aircraft, a gyro rotor supported within said casing by inner and outer gimbals, means movable with said casing about the roll axis of said aircraft for case erecting said rotor, and means positioned by said rotor for controlling the roll attitude of said aircraft.

5. In a gyroscopic navigational instrument for an aircraft, a casing rigidly secured to said aircraft, a yro rotor supported within said casing by inner and outer gimbals, a pendulous bail pivotally mounted about the pitch axis of said aircraft, erector means carried by said bail to case erect said rotor about the roll axis of said aircraft, and means responsive to the position of said rotor about the roll axis for controlling the roll attitude of said aircraft.

6. In a gyroscopic navigational instrument for an aircraft, a casing rigidly supported by an aircraft, a gyro rotor supported within said casing by inner and outer gimbals, means for case erecting said rotor in roll and gravity erecting said rotor in pitch and means responsive to the position of said gyro rotor for controlling both the roll and pitch attitude of said aircraft.

7. In a gyroscopic navigational instrument for an aircraft as defined in claim 6 wherein said last mentioned means includes manually movable means for changing the pitch or roll of said aircraft.

8. In a gyroscopic navigational instrument for an aircraft, a casing supported by said aircraft, a gyro rotor supported within said casing by inner and outer gimbals, a single means for case erecting said gyro rotor about the roll axis of said aircraft and simultaneously gravity erecting said gyro rotor about the pitch axis of said aircraft, means associated with said gyro rotor for maintaining a fixed roll attitude for said aircraft and means associated with said gyro rotor for maintaining a fixed pitch attitude for said aircraft.

9. In a gyroscopic navigational instrument for an aircraft, a casing supported by said aircraft, a gyro rotor supported within said casing by inner and outer gimbals, means for case erecting said gyro rotor about the roll axis of said aircraft to a position in space that provides a straight flight reference for the aircraft, means for gravity erecting said gyro rotor about the pitch axis of said aircraft to a position that provides a level flight reference for the aircraft and means responsive to said gyro rotor position to maintain the aircraft on a straight and level course.

10. In a gyroscopic navigational instrument, a casing rigidly secured to an aircraft, a gyro rotor supported within said casing by inner and outer gimbal, means for case erecting said rotor about the roll axis of said aircraft and gravity erecting said rotor about the pitch axis of said aircraft, means positioned by said rotor for controlling the roll and pitch of said aircraft and means responsive to atmospheric pressure for controlling the altitude Of said aircraft.

11. In combination, a casing rigidly supported by an aircraft, a gyro rotor supported within said casing by inner and outer gimbals, means for 113 saidaircraftiand'gravityerectingsaid:rotorabout theLpitch axis :of "saidiaircraft' and means 'positionedrbyisaid rotor; to visually indicate :the roll and pitch attitude of said aircraft.

12. In combination, agyro casing carried :by an aircraft, .a gyro rotorrsupported within said casing by inner andiouter gimbals, imeans for case iere'ctingisaid gyro -rotor'about the roll axis of said aircraft and gravity z-erecting said ggyro rotor :about the pitch axis of said aircraft, first means positioned by said rotor with respect to said .roll axis, second ,meansimovable with said aircraft aboutits roll axisiandcoacting with said firstimeans to correct for turning movements of said aircraft,: third means :positioned by said rotor with respect to said pitch axis, and fourth'means movable with said :aircraftabout its pitch axis andcoacinng with said third means to correct for ipitching movements. of said aircraft.

,13.lIn the combination of claim 12 wherein said second .means :includes manually operated means'iforrchanging the roll attitude of said aircraft and said fourth :means includes manually operated means for changing the pitch attitude of said aircraft.

14. In the combination of claim 12, fifth means responsive to changes in atmospheric pressure for adjustingsaid fourth means to maintain said aircraft at a desired altitude.

15.- In a gyroscopic navigational instrument for an aircraft, a casing rigid with said aircraft, a gyro rotor supportedwithin said casing by inner and outer gimbalsmeans for rotating said rotor about'its spinaxis, a single "pendulous bail pivotallysupported about-the-pitchaxis of said aircraft, erecting-means carried Ibysaid bail to case erect said spin axis about the roll axis of said aircraft and gravity erect sa-idspin axis about the pitch "axis of said aircraft-said spin axis being moved by said erectingmeans-to its straight flight L reference position during straight flight of said aircraft, first means positioned by said rotor with respect to said roll axis, second means movable with said aircraft about its roll axis and coacting with said first means to correct for deviations of said aircraft from straight flight, third means positioned by said rotor with respect to said pitch axis and fourth means movable with said aircraft about its pitch axis and coacting with said third means to correct for deviations of said aircraft from level flight.

16. In a gyroscopic navigational instrument as defined in claim 15 wherein said second means includes manually operated means for changing the roll attitude of said aircraft and said fourth means includes manually operated means for changing the pitch attitude of said aircraft.

17. In a gyroscopic navigational instrument for an aircraft, a casing rigid with said aircraft, a gyro rotor supported Within said casing by inner and outer gimbal, means for rotating said rotor about its spin axis. a pendulous bail pivotall supported about the pitch axis of said aircraft so as to be gravity sensitive about said pitch axis, said bail following movements of said aircraft about the roll axis, a frictional erector means carried by said bail and continually in contact with said rotor to case erect said rotor about the roll axis and gravity erect said rotor about the pitch axis, first means movable with said aircraft about its roll axis to sense turning movements of said aircraft and second means movable with said aircraft about its pitch axis to sense pitching movements of said aircraft.

18. In a gyroscopic navigational instrument for an'raircraft, a casing,a gyro rotorsupportedawithin'said casing by inner "and outergimbalsand having a dome attached thereto, said outer ,g'imbal axis lying along the transverse axisof sai'd'aircraft, .a pendulum bailpivotally mounted about the "outer gimbal axis and carrying-an erector, said erector being in continuous contact withsaid dome to'case erect saidgyro 'rotor'about the roll axis of'said aircraft-and toigra'vity ere'ctsaidgyro rotor about the pitch axis of said aircraft, a first potentiometer winding mounted on said casing and coacting with a first wiper arm "carriedwby said outer gimbal, a secondpotentiometer'winding mounted on said outer gimbaland coacting with a second wiper armlcarried by said inner gimbal, a pitch servo connected "to said :firstmotentiometer winding and responsive .to ,movements of said first winding with respect to said first wiper arm to control the pitch attitudeof said aircraft, a roll servo connectedto 531(1360". 0nd potentiometer winding and responsive to movements of said second winding with respect to'said secondarm to control therollattitudeof said aircraft.

19. In'combination, a casing secured $031131!- craft, a gyro rotor supported within'said casing by inner and outer gimbals, asingle means for case erecting said rotor about the roll axisof said aircraft and simultaneously gravity erecting said gyro rotor about the pitch axis of said air-- craft, a potential source positioned by said rotor, a winding in contact withsaid source and movable with said'aircraft aboutone of its 'axis, a servo connected to both ends of said winding, a manually operable potentiometer interposed between one end of said winding and said servo, the output of said servo being varied-by movements of said winding .and'by adjustments ofsaid potentiometer.

20. In a gyroscopic navigational instrument for an aircraft, a casing supported by said aircraft, a gyro rotor supported within said casing by at least a roll gimbal, means for case erecting said gyro rotor about the roll axis of said aircraft to a straight flight reference position determined by the attitude of said aircraft about the roll axis during straight flight, and means controlled by said gyro rotor when in said reference position to maifrlitain the straight flight attitude of said aircra 21. In a gyroscopic navigational instrument for an aircraft, a casing rigidly secured to said aircraft, a gyro rotor supported within said casing by at least a roll gimbal, erecting means for case erecting said gyro rotor about the roll axis of said aircraft, control means positioned about said roll axis and responsive to the position of said gyro rotor to control the roll attitude of the aircraft and means for biasing said control means to position the aircraft for straight flight.

22. In a gyroscopic navigational instrument for an aircraft, a gyro rotor supported within said casing by at least a roll gimbal, erecting means for case erecting said gyro rotor about the roll axis of said aircraft, potentiometer means for controlling the roll attitude of said aircraft comprising a winding movable with said aircraft about the roll axis and a wiper positioned on said winding by said gyro rotor, and means for biasing said potentiometer means to adjust the roll attitude of said aircraft.

23. In a gyroscopic navigational instrument for an aircraft as defined in claim 22 wherein said biasing means comprises a manually operable potentiometer in series with said winding.

24. In a gyroscopic navigational instrument, a

casing supported by said aircraft, a gyro rotor supported within said casing by at least a roll gimbal, a pendulous bail pivotally mounted about the pitch axis of said aircraft, erecting means carried by said bail to case erect said gyro rotor about the roll axis of said aircraft, said rotor being moved to its straight flight reference position during straight flight of said aircraft, first means positioned by said rotor with respect to said r011 axis and second means movable with said aircraft about its roll axis and co-acting with said first means to correct for deviations of said aircraft from straight flight.

25. In a gyroscopic navigational instrument for an aircraft, a casing rigid with said aircraft, a gyro rOtOr universally supported within said casing, means for rotating said rotor about its spin axis, means for case erecting the spin axis of said rotor to a position parallel to the plane of symmetry of the aircraft, and means responsive to the position of said rotor about the roll axis for controlling the roll attitude of said aircraft.

26. In a gyroscopic navigational instrument for an aircraft, a casing rigid with said aircraft, a gyro rotor supported within said casing by inner and outer gimbals, said rotor being rotated about its spin axis, a pendulum pivotally mounted about the pitch axis of said aircraft, erecting means carried by said pendulum for case erecting the spin axis of said rotor about the roll axis of said aircraft to the plane of symmetry of said aircraft, and means responsive to the position of said rotor about the roll axis for controlling the roll attitude of said aircraft.

27. In a gyroscopic navigational instrument for an aircraft, a casing rigid with said aircraft, a gyro rotor universally supported within said casing, means for rotating said rotor about its spin axis, means for case erecting said spin axis about the roll axis of the aircraft to where it is in the same fore and aft plane as the vector sum of the aerodynamic lift forces, means to gravity erect said spin axis about the pitch axis of the aircraft so that it is in the same transverse plane as true gravity vertical, and means positioned by said rotor to continually indicate the true roll and pitch attitude of said aircraft.

28. In a gyroscopic navigational instrument for an aircraft, a casing rigid with said aircraft, a gyro rotor universally supported within said casing, means for rotating said rotor about its spin axis, means for case erecting said spin axis about the roll axis of the aircraft to where it is in the same fore and aft plane as the vector sum of the aerodynamic lift forces, means to gravity erect said spin axis about the pitch axis of the aircraft so that it is in the same transverse plane as true gravity vertical, means responsive to the position of said spin axis about the roll axis to maintain the aircraft in a roll attitude required for straight flight, and means responsive to the position of said spin axis about the pitch axis to maintain the aircraft in a pitch attitude required for level flight.

THOMAS 0. SUMMERS, JR.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,190,390 Thirp Feb. 13, 1940 2,297,265 Von Mantueffel Sept. 29, 1942 2,315,501 Crane et a1 Apr. 6, 1943 2,366,543 Meredith Jan. 2, 1945 2,409,875 Martin Oct. 22, 1946 2,443,748 Sanders et a1 June 22, 1948 FOREIGN PATENTS Number Country Date 365,188 Great Britain Dec. 19, 1931 

